/*
 * A JavaScript implementation of the RSA Data Security, Inc. MD5 Message
 * Digest Algorithm, as defined in RFC 1321.
 * Copyright (C) Paul Johnston 1999 - 2000.
 * Updated by Greg Holt 2000 - 2001.
 * See http://pajhome.org.uk/site/legal.html for details.

The BSD License
---------------
Copyright (c) 1998 - 2002, Paul Johnston & Contributors
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, 
are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list 
of conditions and the following disclaimer. Redistributions in binary form must 
reproduce the above copyright notice, this list of conditions and the following 
disclaimer in the documentation and/or other materials provided with the distribution. 

Neither the name of Paul Johnston nor pajhome.org.uk nor the names of its contributors 
may be used to endorse or promote products derived from this software without specific 
prior written permission. 

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY 
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 
BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 
DAMAGE. 

JavaScript MD5 
--------------
The JavaScript code implementing the algorithm is derived from the C code in RFC 1321 
and is covered by the following copyright: 

Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All rights reserved. 
License to copy and use this software is granted provided that it is identified as 
the "RSA Data Security, Inc. MD5 Message-Digest Algorithm" in all material mentioning 
or referencing this software or this function.

License is also granted to make and use derivative works provided that such works are 
identified as "derived from the RSA Data Security, Inc. MD5 Message-Digest Algorithm" 
in all material mentioning or referencing the derived work.

RSA Data Security, Inc. makes no representations concerning either the merchantability 
of this software or the suitability of this software for any particular purpose. It is 
provided "as is" without express or implied warranty of any kind.

These notices must be retained in any copies of any part of this documentation and/or 
software. 

This copyright does not prohibit distribution of the JavaScript MD5 code under the 
BSD license. 
 */

/*
 * Convert a 32-bit number to a hex string with ls-byte first
 */
var hex_chr = "0123456789abcdef";
function rhex(num)
{
  str = "";
  for(j = 0; j <= 3; j++)
	str += hex_chr.charAt((num >> (j * 8 + 4)) & 0x0F) +
		   hex_chr.charAt((num >> (j * 8)) & 0x0F);
  return str;
}

/*
 * Convert a string to a sequence of 16-word blocks, stored as an array.
 * Append padding bits and the length, as described in the MD5 standard.
 */
function str2blks_MD5(str)
{
  nblk = ((str.length + 8) >> 6) + 1;
  blks = new Array(nblk * 16);
  for(i = 0; i < nblk * 16; i++) blks[i] = 0;
  for(i = 0; i < str.length; i++)
	blks[i >> 2] |= str.charCodeAt(i) << ((i % 4) * 8);
  blks[i >> 2] |= 0x80 << ((i % 4) * 8);
  blks[nblk * 16 - 2] = str.length * 8;
  return blks;
}

/*
 * Add integers, wrapping at 2^32. This uses 16-bit operations internally 
 * to work around bugs in some JS interpreters.
 */
function add(x, y)
{
  var lsw = (x & 0xFFFF) + (y & 0xFFFF);
  var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
  return (msw << 16) | (lsw & 0xFFFF);
}

/*
 * Bitwise rotate a 32-bit number to the left
 */
function rol(num, cnt)
{
  return (num << cnt) | (num >>> (32 - cnt));
}

/*
 * These functions implement the basic operation for each round of the
 * algorithm.
 */
function cmn(q, a, b, x, s, t)
{
  return add(rol(add(add(a, q), add(x, t)), s), b);
}
function ff(a, b, c, d, x, s, t)
{
  return cmn((b & c) | ((~b) & d), a, b, x, s, t);
}
function gg(a, b, c, d, x, s, t)
{
  return cmn((b & d) | (c & (~d)), a, b, x, s, t);
}
function hh(a, b, c, d, x, s, t)
{
  return cmn(b ^ c ^ d, a, b, x, s, t);
}
function ii(a, b, c, d, x, s, t)
{
  return cmn(c ^ (b | (~d)), a, b, x, s, t);
}

/*
 * Take a string and return the hex representation of its MD5.
 */
function calcMD5(str)
{
  x = str2blks_MD5(str);
  a =  1732584193;
  b = -271733879;
  c = -1732584194;
  d =  271733878;

  for(i = 0; i < x.length; i += 16)
  {
	olda = a;
	oldb = b;
	oldc = c;
	oldd = d;

	a = ff(a, b, c, d, x[i+ 0], 7 , -680876936);
	d = ff(d, a, b, c, x[i+ 1], 12, -389564586);
	c = ff(c, d, a, b, x[i+ 2], 17,  606105819);
	b = ff(b, c, d, a, x[i+ 3], 22, -1044525330);
	a = ff(a, b, c, d, x[i+ 4], 7 , -176418897);
	d = ff(d, a, b, c, x[i+ 5], 12,  1200080426);
	c = ff(c, d, a, b, x[i+ 6], 17, -1473231341);
	b = ff(b, c, d, a, x[i+ 7], 22, -45705983);
	a = ff(a, b, c, d, x[i+ 8], 7 ,  1770035416);
	d = ff(d, a, b, c, x[i+ 9], 12, -1958414417);
	c = ff(c, d, a, b, x[i+10], 17, -42063);
	b = ff(b, c, d, a, x[i+11], 22, -1990404162);
	a = ff(a, b, c, d, x[i+12], 7 ,  1804603682);
	d = ff(d, a, b, c, x[i+13], 12, -40341101);
	c = ff(c, d, a, b, x[i+14], 17, -1502002290);
	b = ff(b, c, d, a, x[i+15], 22,  1236535329);    

	a = gg(a, b, c, d, x[i+ 1], 5 , -165796510);
	d = gg(d, a, b, c, x[i+ 6], 9 , -1069501632);
	c = gg(c, d, a, b, x[i+11], 14,  643717713);
	b = gg(b, c, d, a, x[i+ 0], 20, -373897302);
	a = gg(a, b, c, d, x[i+ 5], 5 , -701558691);
	d = gg(d, a, b, c, x[i+10], 9 ,  38016083);
	c = gg(c, d, a, b, x[i+15], 14, -660478335);
	b = gg(b, c, d, a, x[i+ 4], 20, -405537848);
	a = gg(a, b, c, d, x[i+ 9], 5 ,  568446438);
	d = gg(d, a, b, c, x[i+14], 9 , -1019803690);
	c = gg(c, d, a, b, x[i+ 3], 14, -187363961);
	b = gg(b, c, d, a, x[i+ 8], 20,  1163531501);
	a = gg(a, b, c, d, x[i+13], 5 , -1444681467);
	d = gg(d, a, b, c, x[i+ 2], 9 , -51403784);
	c = gg(c, d, a, b, x[i+ 7], 14,  1735328473);
	b = gg(b, c, d, a, x[i+12], 20, -1926607734);
	
	a = hh(a, b, c, d, x[i+ 5], 4 , -378558);
	d = hh(d, a, b, c, x[i+ 8], 11, -2022574463);
	c = hh(c, d, a, b, x[i+11], 16,  1839030562);
	b = hh(b, c, d, a, x[i+14], 23, -35309556);
	a = hh(a, b, c, d, x[i+ 1], 4 , -1530992060);
	d = hh(d, a, b, c, x[i+ 4], 11,  1272893353);
	c = hh(c, d, a, b, x[i+ 7], 16, -155497632);
	b = hh(b, c, d, a, x[i+10], 23, -1094730640);
	a = hh(a, b, c, d, x[i+13], 4 ,  681279174);
	d = hh(d, a, b, c, x[i+ 0], 11, -358537222);
	c = hh(c, d, a, b, x[i+ 3], 16, -722521979);
	b = hh(b, c, d, a, x[i+ 6], 23,  76029189);
	a = hh(a, b, c, d, x[i+ 9], 4 , -640364487);
	d = hh(d, a, b, c, x[i+12], 11, -421815835);
	c = hh(c, d, a, b, x[i+15], 16,  530742520);
	b = hh(b, c, d, a, x[i+ 2], 23, -995338651);

	a = ii(a, b, c, d, x[i+ 0], 6 , -198630844);
	d = ii(d, a, b, c, x[i+ 7], 10,  1126891415);
	c = ii(c, d, a, b, x[i+14], 15, -1416354905);
	b = ii(b, c, d, a, x[i+ 5], 21, -57434055);
	a = ii(a, b, c, d, x[i+12], 6 ,  1700485571);
	d = ii(d, a, b, c, x[i+ 3], 10, -1894986606);
	c = ii(c, d, a, b, x[i+10], 15, -1051523);
	b = ii(b, c, d, a, x[i+ 1], 21, -2054922799);
	a = ii(a, b, c, d, x[i+ 8], 6 ,  1873313359);
	d = ii(d, a, b, c, x[i+15], 10, -30611744);
	c = ii(c, d, a, b, x[i+ 6], 15, -1560198380);
	b = ii(b, c, d, a, x[i+13], 21,  1309151649);
	a = ii(a, b, c, d, x[i+ 4], 6 , -145523070);
	d = ii(d, a, b, c, x[i+11], 10, -1120210379);
	c = ii(c, d, a, b, x[i+ 2], 15,  718787259);
	b = ii(b, c, d, a, x[i+ 9], 21, -343485551);

	a = add(a, olda);
	b = add(b, oldb);
	c = add(c, oldc);
	d = add(d, oldd);
  }
  return rhex(a) + rhex(b) + rhex(c) + rhex(d);
}
